Subject: RE: gaussian: electron density

From: "Shobe, Dave" <[email-masked]>
Date: Mon, 04 Mar 2002 09:04:09 -0500

The "elecron densities at the oxygen of the carboxylate" is ambiguous, as
the electron density varies from point to point.  The only unique point I
can think of is the oxygen nucleus, but I suspect you'd more more interested
in the "lone pair" area.  Calculation of the electron density at a point is
trivial; defining the point to use in a way that's consistent from molecule
to molecule is the challenge.

Yes, CHELPG is based on electrostatic potentials--although I would think
those would be important in binding to Zn+2 also.  It might be interesting
to see which is more important.

Come to think of it, I vaguely remember some kind of function, related to
AIM analysis (atoms-in-molecues, based on the eletcron density distribution)
that had a maximum in lone pair regions of a molecule.  I don't remember any
details and I'm not even sure what I recall is accurate, but it might be
worth a trip to the library (or SciFinder) to investigate.

--David Shobe
Süd-Chemie Inc.
phone (502) 634-7409
fax     (502) 634-7724
email  [email-masked]

Don't bother flaming me: I'm behind a firewall.

-----Original Message-----
From: Donald Keidel [mailto:[email-masked]]
Sent: Friday, March 01, 2002 1:45 PM
To: [email-masked]
Subject: CCL:gaussian: electron density

Hello all,

I want to use Gaussian to calculate or determine the electron density on the
oxygen atoms of benzoic acids.  I want to do this for various benzoic acids
that are different from eachother only in their substitution at the ortho
meta and para positions.  I think that benzoic acids with different elecron
densities at the oxygen of the carboxylate of the benzoate will coordinate
to zinc differently with different affinities.  I might be wrong.  What
method in Gaussian 98 is best suited for this.  I was told to use CHELPG,
but I believe that is used for electrostatic potentials and not electron
densities.  Thank you to all.  Have a good day.

Don
---------------------------------------------------
Donald J. Keidel
University of California, Riverside
Department of Biochemistry and Molecular Biology
Riverside, CA 92521
phone:  (909) 787-5493
fax:  (909) 787-4434
[email-masked]
webpage: www.biochemistry.ucr.edu/gru/gradstudents/don_keidel/index.htm